Process for the polymerization of furfuryl acrylate



Patented Nov. 23, r 1948 PROCESS FOR THE POLYMERIZATION OF FUBFURYIIACRYLATE Ghessie E. Rehber'g, Philadelphia, and Charles H. Fisher,Abington, Pa., assignors to the United States of America as representedby the Secretary of Agriculture No Drawing. Original applicationDecember 27, 1943, Serial No. 515.798, now Patent No.

2,433,866, January 6, 1948. Divided and this application December 18,1945, Serial No.

. 4 Claims.

(Granted under the act of March amended April 30, 1928; 370 0.

This application is made under the act of March 3, 1883, as amended bythe act of April 30, 1928, and the invention herein described, ifpatented, may be manufactured and used by or for the Government of theUnited States of America for governmental purposes without the paymentto us of any royalty thereon.

This is a division of our copending application for patent, Serial No.515,798, filed December 27, 1943, Patent Number 2,433,866 issued January6, 1948.

This invention relates to furfuryl acrylate, a new composition ofmatter.

An object of this invention is to provide a new polymerizablecomposition of matter together with processes for its preparation andpolymerization.

Other objects will appear from the following description.

We have found that furfuryl acrylate, which may be prepared by analcoholysis reaction of methyl acrylate with furfuryl alcohol, is avaluable polymerizable compound.

The alcoholysis reaction is suitably carried out by heating furfurylalcohol with an excess of methyl acrylate in the presence of an esterinterchange catalyst and a polymerization inhibitor, removing themethanol formed by distillation of its azeotrope with methyl acrylate,and then recovering thefurfuryl acrylate by fractional distillation.Aluminum alcoholates,,such as aluminum tertiary-butoxide, are effectivecatalysts for the reaction, and the alcoholates of other metals, such assodium and potassium, also give good results. Aromatic amines andphenols are examples of convenient polymerization inhibitors.

This method of preparing furfuryl acrylates is illustrated by thefollowing example:

Example I proximately 120 C., under a fractionating 001- 3, 1883, as G.757) umn fitted with a condenser arranged for controlling reflux. Thedistillate was collected at such a rate that the temperature of thevapor at the head of the column remained at or'near the boiling point ofthe methanol-methyl acrylate binary azeotrope (62 C.). When theproduction, of methanol had practically ceased, the excess methylacrylate was distilled out of the mixture and the furfuryl acrylate wasdistilled under reduced pressure. Purified furfuryl acrylate has aboiling point of 93 C. at 16 mm., and at 20 C. it has a density of1.1125 g. per cc. and a refractive index for the D line of sodium of1.4800. The yield was 131 parts, or 86 percent of the theoretical.

The procedure outlined in Example I can be advantageously modified byremoving methanol from the reaction mixture as an azeotrope with analiphatic hydrocarbon of suitable boiling range,

rather than as an azeotrope with methyl acrylate. This is the subject ofa copending application for patent by Chessie E. Rehberg, Serial No.515,799, filed December 27, 1943, now Patent No. 2,406,561, August 27,1946. Also, furfuryl acrylate may be prepared by other methods. Anysuitable esterlfication or ester interchange process may be used.

Monomeric furfuryl acrylate is a colorless, mobile liquid which may bepolymerized with heat, light, and/or catalysts. Characteristically, acatalyst such as a peroxide, an ozonide, oxygen or ozone is'employed.The polymerization may be effected in the presence or absence of asolvent or diluent, or the monomer may be emulsified and thenpolymerized. Preferably, polymerization is carried out at moderatetemperatures, that is, about 50 tolOO" C.

Furfuryl acrylate may also be copolymerized with a variety of otherpolymerizable compounds, such as other esters of acrylic or methacrylicacid. Since furfuryl acrylate has a multiplicity of polymerizable doublebonds in its molecule, it is capable of forming cross-linked polymersand copolymers. If desired, so-called polymerization regulators, such aspolychloro hydrocarbons and mercaptans, may be added to the monomer toaid in preventing or controlling cross linkage.

Relatively small proportions of furfuryl acrylate in other polymerizablemonomers such as the alkyl acrylates and methacrylates, produce ap-'Example II 19 volumes of methyl acrylate and 1 volume of iurfurylacrylate were dissolved in 80 volumes of ethyl acetate. 0.25 volume ofbenzoyl peroxide was then added and the solution was placed on a waterbath which was maintained at 70 C. After 24 hours the entire solutionhad set to a stilt.

colorless, transparent gel which was relatively insoluble in the commonorganic solvents. After the ethyl acetate had been allowed to evaporate,the polymer was obtained as a tough, elastic, transparent solid whichwas harder, tougher, and less soluble than methyl acrylate polymers.

Example III A copolymer of furfuryl and methyl acrylates were preparedas in Example II, except that to the monomer solution there was added0.1 volume of dodecyl mercaptan. The polymer thus obtained did not gelthe ethyl acetate solution, forming instead a viscous, sirupy truesolution. A film prepared Irom this solution by evaporation of thesolvent was clear, colorless, flexible, and elastic.

The properties of the polymers obtained by polymerization of furfuryl:acryla'te, with or without other monomers, can be controlled over awide range of hardness, solubility, fusibility, elasticity, and soforth, by variation of the polymerizing process, addition of othermonomers, solvents, fillers, dyes, plasticizers, and other modificationsof the process which are well known to those skilled in the art.

The polymers of furiuryl acrylate, and especially its copolymers withother polymerizable compounds, are valuable for moldings, extrusions,coatings, and thelike. The peculiar type and degree of unsaturation inthe furfuryl radical makes this acrylate particularly valuable forcopolymerization with other monomers. Under certain polymerizingconditions, as for instance in Example II, cross-linkage may be obtainedin the polymer in a degree which is controllable within wide limits.Under other conditions, as illustrated by Example III, the cross-linkagemay be partially or entirely prevented. The polymer thus obtainedprobably contains the iurfuryl radical intact and hence is unsaturated.This linear, unsaturated polymer may be vulcanized with sulfur or otherknown vulcanizing agents to produce an elastic, rubber-like product.Such vulcanization, and the incident curing, milling, and so forth, maybe carried out with the agents, equipment, and procedures used insimilar operations on natural rubber.

Polymers of the type formed by furfuryl acrylate might also be formedwith the substituted furfuryl acrylates. For example, alkyl furfurylacrylates, dialkyl furfuryl :acrylates, and halogensubstituted furfurylacrylates contain the same pattern of unsaturation as is found infurfuryl acryla'te, and they would accordingly be expected to polymerizeand copolymerize to form resins of the same general type.

Having thus described our invention, we claim:

1. A process comprising copolymerizing a mixure containing, as thepolymerizable constituents, at least methyl acrylate, the balance beingfurfuryl acrylate, by heating the mixture in the presence of a peroxidecatalyst.

2. The process of claim 1 in which the copolymerization is in thepresence of the polymerization regulator dodecyl mercaptan.

3. A copolymer the polymerizable constituents of which are at least 95%methyl acrylate and the balance being furfuryl acrylate.

4. A vulcaniza-ble copolymer the polymerizable constituents of which areat least 95% methyl acrylate and the balance being furfuryl acrylate,the copolymerization of said constituents being carried out in thepresence of the polymerization regulator dodecyl mercaptan.

CHESSIE E. REHBERG.

CHARLES H. FISHER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,129,667 Barrett Sept. 13, 19382,281,613 Wollthan Mar. 5, 1942 2,395,017 Semon Feb. 19, 1946 (filedDec. 26, 1942)

